It is already known that olefins can be arylated by bromoaromatics in the presence of palladium catalysts, phosphine ligands and a base (see R. F. Heck, Org. React. 27, 345-391 (1982)).
Furthermore, for example, EP 0 078 768 and EP 0 103 544 describe Heck couplings between 4-substituted aryl halides and acrylic acid derivatives.
However, these references give no indication that this process can also be used for aryl halides which have an alkenyl group possibly capable of a Heck coupling in the 4-position relative to the halogen atom.
DE 34 45 365 describes the preparation of the compounds of the formula I in which Z is a group of the formula II in a complicated 4-stage process starting from 4'-ethylbenzylidenecamphor, which additionally includes two Wittig reaction steps.
There is therefore a need for a process by means of which the compounds of the formula I can be prepared in fewer process steps, in high space-time yields and using no auxiliaries requiring particular outlay.